The subject matter disclosed herein relates generally to turbine engines and, more specifically, to exhaust systems for use with turbine engines.
Rotary machines, such as steam turbines, may be used to generate power for electric generators. Known steam turbines have a steam path defined within a shell that includes, in serial-flow relationship, an inlet, at least one turbine, and an outlet. Known turbines include at least one row of circumferentially-spaced rotating buckets or blades.
During low-load and/or start up conditions, steam leakage may occur near the inlet due to the high pressure of the incoming steam. Moreover, during the same operating conditions, because a low pressure (LP) section of the turbine is under vacuum, an undesirable amount of atmospheric air may be drawn into the turbine system. At least some known turbine configurations include redundant steam seal systems that facilitate reducing steam leakage during low-load and start up operating conditions. For example, at least some known steam seal systems supply low pressure steam to the steam seals during pre-determined operating conditions. The low pressure steam prevents the ingress of atmospheric air into the LP section of the steam turbine and helps maintain a positive pressure at the high pressure (HP) section of the steam turbine. As turbine load is increased, only a portion of the high pressure and temperature steam directed from the steam seal header is used for sealing purposes, and the remainder is channeled to the condenser. At least some known steam turbines also include an exhaust hood downstream from a last stage of the turbine. Known exhaust hoods help recover the static pressure of the steam and also guide the steam from the last stage of the turbine to the condenser. However, at least some known exhaust hoods require steam to turn about 90° towards the condenser. The abrupt change in the direction of the steam flow may cause the flow of steam to separate within the hood. Flow separation may reduce static pressure recovery and reduce turbine efficiency.